Mounting tissue



Patented Sept lZ, 1 944 Moim'rmG TISSUE Allen Abrams and George W. Forccy, Wausau,

Wis., assignors to MarathonPaper Mills Company, Rothschild, Wis, a corporation of Wisconsin No Drawing. Application November 30, 1942, Serial No. 467,464

7 Claims.

This invention relates to mounting tissu for use in afiixing photographs, pictures, maps, printed matter, and the like, to any desired base by means of heat and pressure.

Heretofore, several types of mounting tissues have been available, but each of them had cer-' tain inherent characteristics which rendered them either inconvenient to us or which developed defects that vitiated their utility. For

example, one type of mounting tissue consists of a dense sheet of paper coated on both sides with a heat-scalable lacquer coating. This coating is tacky under normal conditions and it is therefore necessary to interleave the mounting tissue sheets with separator or slip-sheets to prevent the sheets from sticking or blocking to eachother when stacked. When such sheets are used it is necessary to remove and discard the individual separator sheets, so that the work in mountingphotographs and the like is delayed by unnecessary manipulations,

Another type of mounting tissue utilizes coatings of wax compositions containing rubber. Although such coatings provide good bonds when first made, they loosen with temperatur changes and also tend to weaken with age.

In accordance with the present invention w provide a mounting tissue which overcomes the disadvantages previously mentioned. Our mounting tissue is non-tacky at normal temperatures; it requires no slip-sheet to prevent blocking; it is flexible; it does not become brittle and is not affected by moisture, sunlight, or air. Our mounting tissue provides a strong adhesiv bond which is not impaired by temperature changes, humidity or age. Our mounting tissue can be used for afiixing photographs, pictures, maps and similar articles to any base material by heat and pressure without discoloring, staining or damaging the article mounted. Our mounting tissue obviates the need for expensive presses required for mounting articles with previous typ s of mounting tissues. Our mounting tissue can be used with simple inexpensive equipment,. such as a hand-iron.

Our mounting tissue is made from a selected cellulosic base sheet material, which may be a dense sheet material, such as glassine, Cellophane (regenerated cellulose), or a porous type of sheet material, such as paper. We prefer to greater amount of bondin composition than a cially prepared hot-melt composition so as to provide the bonding means for afflxing articles with our mounting tissue. The composition consists essentially of ethyl ether of cellulose, a plasticizer and a compatible non-volatile solvent.

The proportion ofingredients of our composition may be varied over a considerable range.

dense sheet and will therefore give a stronger 1 bond.

The base sheet material is treated with a spe- The ethyl cellulose may constitute about 15 to about 50% by weight of the composition. We prefer to use ethyl cellulose having an ethoxyl content of about 40 to about 50% by weight. The plasticizer, such as hydrogenated methyl abietate, tri-phenyl phosphate, di-(para tertiarybutyl-phenyl) mono-phenyl phosphate, di-phenyl mono-(ortho-xenyl) phosphate, di-(ortho xenyl) mono-phenyl Phosphate, may constitute from about 15 to about 50% by weight of the composition. The non-volatile solvent, such as hydrogenated oils, hydrogenatedcastor oil, and stearic acid, may be used in amountsfrom about 20 to about by weight of the composition.

The following are specific examples of hotmelt compositions suitable for treating porous sheets, such as paper.

In preparing the composition, the plasticizer is first heated to about 200 F., the hydrogenated castor oil and the ethyl cellulose added, and the mixture is stirred until it is entirely free of lumps. This may require from about one to four hours, depending upon the size of the ethyl cellulose particles used. The resulting composition is clear and homogeneous and has a viscosity of about 100,000 centipoises or higher; at 200 F. as determined by Brookfield Synchro-lectric viscosimeter using 1 R. P. M. spindle speed. The molten composition is then applied in any suitable manner to both sides of the base-sheet so as to distribute the composition uniformly in the sheet as well as on both its surfaces. When paper is to be treated, for example, the composition may be fed betweentwo hot rotating rolls and the paper passed between the nip of the rolls so that both sides of the paper ar coated smoothly. The treated paper is then passed over a chilled roll to harden the composition, and it as a carrier for the composition. When the composition isapplied to paper, we find it advantageous to have the sheet carry about 30 lbs. per ream (24 x 36-480).

Upon application of heat and pressure, our

mounting tissue afllxes articles securely to any suitable base, because the composition on the surface provides a direct bond between the article being mounted and the mounting tissue, as well as between the base surface to which the mounting tissue is attached. Our composition also reinforces and unifies the fibers of the base sheet so that the base sheet will not split or separate when the mounted article is subjected to a pulling force.

When a photograph, picture, map, printed matter or any desired flat sheet or article is to be aiiixed to any desired base. the mounting tissue, cut to suitable dimension and contour, is placed on the base, the article to be afllxed is then superimposed on the mounting tissue whereupon heat and pressure are applied by any suitable means. For example, an ordinary fiat-iron, heated to.250 F., is suflicient to produce an excellent bond. After mounting in the manner described, the afilxed article will adhere firmly under wide extremes of ordinary temperature and humidity. The bond will notbe aflected by exposure to sunlight or air and it will last indefinitely. The aillxed article may be removed readily from the base by merely applying heat which will soften the thermoplastic composition to permit the article to be detached intact and unimpaired. 1

It is to-be understood that changes and modifications may be made within the scope of our invention which are intended to be included in the appended claims.

We claim:

1. A mounting tissue for photographs and printed matter comprising a cellulosic base sheet carrying a uniformly distributed hot-melt composition at both surfaces thereof comprising ethyl cellulose from about to about 50% by weight, a plasticizer from about 15 to about 50% by weight and a compatible non-volatile solvent from about to about 60% by weight.

surfaces thereof comprising ethyl cellulose from about 15 to about 50% by weight, a plasticizer from about 15'to about 50% by weight and a compatible non-volatile solvent from about 20 to about by weight.

4. A mounting tissue for photographs and printed matter comprising a fibrous sheet carrying a uniformly distributed hot-melt composition at both surfaces thereof comprising a fibrous sheet carrying a uniformly distributed hot-melt composition comprising ethyl cellulose from about 15 to about 50% by weight, an aromatic phosphate from about 15 to about 50% by weight and a hydrogenated castor oil from about 20 to about 60% by weight.

5. A mounting tissue for photographs and printed matter comprising a cellulosic base sheet carrying a uniformly distributed hot-melt composition at both surfaces thereof comprising ethyl cellulose having an ethoxyl content of about 40 to 50% by weight 25% by weight, di-(ortho xenyl) monophenyl phosphate 35% by weight, and hydrogenated castor oil 40% by weight.

6. A mounting tissue for photographs and printed matter comprising a cellulosic base sheet carrying a uniformly distributed hot-melt composition at both surfaces thereof comprising ethyl cellulose from about 15 to about 50% by weight, a plasticizer from about 15 to about 50% by weight and hydrogenated castor oil from about 20 to about 60% by weight.

7. A mounting tissue for photographs and printed matter comprising a base sheet carrying a uniformly distributed hot-melt' composition at both surfaces thereof comprising ethyl cellulose (40 to 50% by weight of ethoxyl content) from about 15 to about 50% by weight, a plasticizer from about 15 to about 50% by weight and hydrogenated castor oil from about 20 to about 60% .by weight.

ALLEN ABRAMS. GEORGE W. FORCEY. 

